The present invention relates generally to the printing of documents, such as negotiable instruments, that include security features, and more particularly to fonts for documents having one or more regions upon which secure transactional text is printed, such text comprising both human-readable attributes and machine-readable attributes to deter unauthorized duplication or alteration of the documents, as well as to self-authenticate transactional content within the font.
The use of security features for sensitive documents, such as checks or related negotiable documents, has been known in the art for some time. Typically, these sensitive documents will include a preprinted, patterned background and one or more transactional data fields onto which human-readable text is subsequently added by known means, such as computer-based printing. One conventional feature used to thwart unauthorized duplication or reproduction involves the use of latent pantographic images that reveal themselves upon processing the document through a copier, scanner or related device. Such pantographic images are designs that take advantage of the inherent limitations in the resolution thresholds of copying and scanning devices. Security image elements (such as lines or dots) exceeding such resolution threshold are interspersed into a document background made up of smaller security image elements such that the image formed by the larger security image elements is not readily apparent on the original, but manifests itself on the face of the reproduced document, making it apparent to even a casual observer that the document is not an original. Typically, these indicia will be in the form of a recognizable stock warning, such as “VOID” or “COPY”.
Variations on this approach include the use of shaded and multi-colored surfaces, repeating pattern backgrounds, document-embedded objects and watermarks. For example, a blended or rainbow color scheme with graduated colors over the surface of the document, by virtue of subtle shading differences, is not easily copied. Similarly, the placement of an embedded object, such as a strip, or a watermark, neither of which shows up on a reproduced document, can be verified quickly by visual inspection. Additional warnings on the face of the document may be used to alert the document recipient to the presence of the strip or mark, and to suggest that its existence be checked for document authentication. Advancements, however, in technically sophisticated reproduction equipment have led to lower resolution thresholds, allowing various settings to be tried until the reproduced document is virtually indistinguishable from the original. Moreover, the incorporation of pantographic images, blended color schemes, watermarks and similar passive background approaches, even if protective of the authenticity of the document, provides no assistance in ascertaining the genuineness of the transactional data printed on such document.
One way to provide transactional data protection is to encode and print machine-readable information onto the surface of the original document, an example of which can be found in U.S. Pat. No. 5,951,055, assigned to the assignee of the present invention. This can be accomplished through the use of an algorithm-driven encoding scheme in conjunction with computer-based printing devices. In such an approach, the algorithm instructs the printer to add visually unobtrusive markings (often called glyphs) into one or more areas of the document. In the present context, a glyph is a mark in the form of a geometric pattern made up from a plurality of individual pixels. Typically, in the case of an elongate mark (such as a line), the glyph is one pixel wide. Based on instructions from an encryption algorithm, these glyph patterns are rearranged in one or more of the gray-scale portions of a printed medium such that a scanning machine equipped with a suitable decryption routine can verify the authenticity of the information contained in the document's human readable characters. For applications where most printing is accomplished with black ink using a high-resolution (i.e., 300 dpi, 600 dpi or higher) print device, these markings can amount to a rearrangement of the dot patterns in the gray scale shadings in such a way that encoded information is juxtaposed with unencoded text dots. The human eye detects what appears to be conventional, unencoded information, while the encoded information is detectable by a machine reader, such as an optical recognition system. Attempts at unauthorized reproduction are hampered by the inability of the copying equipment to faithfully reproduce the glyph patterns.
This encoding approach has the advantage over conventional bar code encryption in that the integration of security information is provided seamlessly, thus adding to the document's aesthetic appeal, as well as providing the option of having no readily-discernable indicia of security information therein. However, surreptitious schemes such as this, while useful for facilitating the detection of the source of unauthorized copying or alteration, do not put a putative forger on notice that the document is possessive of one or more security-enhancing features. This is analogous to protecting a piece of fenced-in property by having a roving guard dog posted, but failing to place a sign on the fence alerting a would-be trespasser to the dog's presence: in both circumstances, while there is ample evidence of both the property being violated and subsequent deployment of the security system after the fact, there is nothing in place to prevent the occurrence of the violation in the first place. Furthermore, while the advent of high-powered computational systems has rendered data glyphs and the algorithms used to generate them timewise and cost effective, the use of relatively insensitive lower resolution printers (such as 180, 200 or 240 dpi, all commonly employed in the banking and check-printing industries) with visually unobtrusive glyphs and related symbols could introduce printing or scanning errors, especially when the glyphs are oriented at angles where they could be confused with printed text or spurious marks.
Accordingly, there exists a need for a font that can be used to print transactional data onto a document such that the printed data includes, or gives the appearance of, additional machine-readable security protection. There exists a further need to present the information contained within the font such that the machine-readable security information can be printed to, and read from, devices of widely-varying resolutions. There also exists a need to provide these capabilities in conjunction with traditional, passive means for human-readable indicia of secure document authenticity.